Answer:
a. the pH within the thylakoid is less than that of the stroma
Explanation:
The pH of thylakoid membrane is 8 at normal conditions but it became highly acidic like 4 during photosynthesis. The electron transport chain utilize the energy released by excited electrons to pump the H+ ions to lumen of thylakoid membrane from stroma during light reaction of photosynthesis. The H+ ions are present in both the stroma and thylakoid membranes. These high potential H+ ions are utilized by ATP synthase complex for the production of ATP.
We know that more the H+ ions lesser will be the pH and lumen have the high concentration of H+ ions. While the pH of stroma is normally kept acidic by plants to create a concentration and potential difference of H+ ions for the production of ATP. That why the lumen have lower pH than stroma of chloroplast.
Answer:
I believe it may be "B" so hopefully it's right
Answer:
adhesion molecules
Explanation:
Cells of multicellular organisms are organized into tissues and organs. This arrangement depends largely on your ability to adhere well to the extracellular matrix or other cells. In animal tissues, adhesion is carried out by means of the so-called adhesion proteins, which are anchored to the plasma membrane. These proteins have enabled the formation of animal bodies, all of them multicellular. In fact, the adhesion molecules of the various groups of animals, including marine sponges, are very similar to each other. <u>The adhesion not only serves to anchor and position the cells to form three-dimensional scaffolds, but also as a form of cellular communication that is to say allows the interaction between the cell and its matrix</u>. That is, the degree of adhesion and to whom the cells adhere is a type of useful information for the cell.
Adhesion also helps cells move through tissue or between tissues. Keep in mind that cells do not travel by swimming but by crawling. Therefore, to move the cells they need to first lose the adhesion that keeps them fixed and then expose other molecules that allow to create anchor points and drag the cytoplasm in the direction of movement. It is interesting that in some circumstances, such as during embryonic development, cells move in groups in a coordinated manner, for which cell-cell adhesions are necessary.
Adhesion proteins are arranged on the cell surface, being able to diffuse laterally through the membrane. When they bind to an extracellular molecule they are anchored. Individually, the force with which they adhere is not very great but since they are many molecules they generate a strong adhesion acting as a Velcro. Some of the adhesion molecules can interact laterally with each other, and with other proteins, to form groups that increase adhesion strength at certain points on the cell surface forming focal junctions and binding complexes.
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